22 FUNCTIONS OF INSECTS. 



haman eye. Many insects still smaller have eyes, so contrived as to discern objects 

 pomp thousands of times less than themselves ; tor such the minute particles on 

 which thef feed must certainly be. 



With respect to the wiiigs of insects, those of the two first orders of Linnaeus 

 Lave their wings defended by a pair of hard crustaceous cases called elytra. The 

 three subsequent orders have four membranaceous wings, without elytra. All tha 

 injects of the sixth order have but two wings, and under each of these, at its base, 

 there is a poise or balancer like a little knob. These poises are commonly little 

 b.ills, each phiced on the top of a slender stalk, and movable every way at pleasure. 

 In some they stand alone, but in others, as in the Flesh-liy tribe, they have litlla 

 Covers or hollow membranaceous scales, each of which somewhat resembles a spoon 

 »vithout a handle : every time the insect strikes the air with its wings, a very quick 

 motion may be perceived in the balancer; and in the Flesh-flies, when this moves, 

 it strikes against the little scale, and thus assists in producing the well-known buzz- 

 ing sound that is made by flies when on the wing. The use of the poises to an 

 insect seems to be precisely the same as that of a long pole, loaded at each end with 

 lead, to a rope-dancer : they render the body steady, and obviate all its unsteadiness 

 in flight. 



The structure of the feet of these diminutive creatures is truly admirable. Those 

 insects that live altogether in water have their feet long, flat, and somewhat hairy 

 at the edges, well adapted to aid their motions in that element. Such as hav« 

 occasion to burrow into the earth have their legs broad, sharp-edged, and serrated. 

 These that use their feet only in v/alking, have them long and cylindrical, yomo 

 have their feet furnished with sharp, hooked claws, and skinny palms, by which, 

 from the pressure of the atmosphere upon them, they are enabled to walk on glass 

 and other smooth surfaces, even with their backs downward. Others have some- 

 what like sponges that answer the same end ; and the spider has each foot armed 

 with a kind of comb, probably for the purpose of separating the six threads that 

 issue from so many orifices of its body, and preventing them from tangling. . In 

 insects which have occasionally to pass over spaces by leaping, the thighs of the 

 hind legs are peculiarly large and thick. 



The tonyui' of insects is a taper and compact instrument, by which they suck 

 their fond. Some of them can contract or expand it ; and others, as the Butter- 

 flies, roll it up under their head, somewhat like the spring of a watch. In many 

 it is enclosed within a sheath; and in several, as the Flies, it is fleshy and tubular. 



The moufh is generally placed somewhat underneath the front part of the head ; 

 out in a few of tiie tribes it is situated below the breast. Some insects have it 

 furnished with a kind of forceps, for the purpose ot seizing and cutting their prey ; 

 and in others it is pointed, to pierce animal or vegetable substances, and suck their 

 juices. In several it is strongly ridged with jaws and teeth, to gnaw and scrape 

 their food, carry burdens, perforate the earth, nay the hardest wood, and even stones, 

 fi r the habitations and nests of their offspring. In a few the tongue is so short as 

 fa appear to u< incapable of answering the purpose for which it is formed ; and the 

 Gadflies appear to have no mouth. 



Near the mouth are situated the palpi or feelers: these are generally four, but 

 sometimes six in number. They are a kind of thread-shaped articuiated antennae. 

 'I'heir situation, beneath and at the sides of the mouth, renders them, however, Buf- 

 flciently distinct from the proper antenna. Some writers consider them to be 

 useful i"c holding food to the mouth, whilst the insects are eating. 



Linnaeus has divided the animals of this class into seven orders,* viz : 

 ■ 1. Coleopterous insects (derived from the Greek words xoXfoj a sheath, and rtttpov 

 B wing.) These are the Beetles, or such as have crustaceous elytra or shells, which 

 Bhut together, and form a longitudinal suture down the back. Of this order are 

 the Chafer tribes, and several others. 



2. Hemipti n-us insects (from r;fu,nvi half, and rtttpov a wing.) have their upper 

 wings half crustaceous, and half membranaceous, not divided by a longitudinal suture, 

 but incumbent on or crossed over each other; as the Cockroach, Locust, itc. 



3. Lepi lopleruus insects (from ntXii a scale, and nrspov a wing,J are those having 



* Coleoptera, Ilemiptera, Lepidoptera, Neuroptera, Hvaaenoptera, Diptera, and Aptera- 



